Success Story - External Emergency Compressed Air Supply for a Briquette Factory - RWE POWER AG

RWE Power AG use six AERZEN screw compressors for external compressed-air emergency supply. Six Aerzen screw compressors for external compressed-air emergency supply, as well as emergency units and diesel tanks were installed on the paved courtyard in front of the central compressed-air station. At its site in Frechen, near Cologne, RWE Power AG processes 5.15 million tons of crude lignite every year into about 900,000 tons of pulverised lignite and 1.1 million tons of briquettes. In a second operational area, the company’s own power plant produces 0.983 terawatt hours of electrical energy every year using briquetting carbon. For 24-hour production at both areas, a fail-safe compressed air supply is a must. This is generated in a central station by three oil-free compressing, speed-controlled Aerzen screw compressors: two units for base and peak load, the third for redundancy. Afterwards the compressed air is dried in three water-cooled adsorption dryers to a pressure dew point of -80 °C, kept available separately as working and instrument air in two compressed air reservoirs and then fed into two separate operating networks. The station works with a pressure of 6.5 bar as only then can the flawless functioning of all the consumers connected within the entire system be guaranteed.

Double dilemma

Dipl. Ing. Christoph Zura, Plant Engineer power plant technology at RWE Power AG: As general contractor, AIR completed the entire project in exemplary fashion: All its promised dates were adhered to precisely. The entire job was completed in one week, including assembly and dismantling of the standby station. In 2012/2013 this concept was systematically reviewed. Leakage was detected in the cooling water system of the three adsorption dryers, which could only be removed during standstill of all three dryers. But, as the compressed air could not be fed into the systems in an undried condition, the standstill of the dryers also meant a standstill of the compressors, the compressed air supply and consequently of the entire production.

Furthermore, the inspection showed that upgrades were also needed in fire protection and asset value protection, which could only be achieved during a two-day complete shutdown of the electrical distribution station. Consequently, the electrical supply of the company’s compressed air station was not available during the repair period. For the repair period an external emergency supply had to be found. The Wachtberg briquette factory has been co-operating with Aerzener Maschinenfabrik for many years now, as Aerzen compressors are not only working in the central compressed air station, but also in the ash-handling plant. So, together with Aerzener they were looking for potential solutions.

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